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i 25 July 2008 AGE-NC Project No. 99-0682 Page 3 of 6 impacted soil at the site; wells VW- I and VW-3 are screened through the lower vadose zone (20 feet to 30 feet bsg) and VW-2 and VW-4 are screened through the shallow vadose zone (10 feet to 20 feet bsg). Based on the results of the SVE pilot tests conducted at the site in July 2008, a theoretical radius of influence (ROI) of lowervadose SVE at the site will be approximately24 feet; a theoretical ROI of upper vadose SVE at the site will be approximately 24 feet. Utilization of wells VW- 1 through VW-4 for an interim remediation SVE system should be adequate to extract soil vapor from the petroleum-impacted soil in the vadose zone beneath the former UST area. 2.3 . INSTALLATION OF INTERIM REMEDIATION SYSTEM PIPING NETWORK Remediation system piping network will be installed underground within a 1 -foot wide by 1 '/z-foot deep trench. In order to minimize flow restrictions and more readily facilitate the reconfiguration of the SVE wells, AGE proposes to install separate piping runs (home-runs) composed of 2-inch diameter, schedule 40 PVC piping from well-heads at VW- 1 through VW-4 to an extraction manifold located inside the proposed remediation enclosure. From the extraction manifold, 2-inch diameter, schedule 40 PVC piping will be routed to the proposed soil vapor extraction unit (thermal/catalytic oxidizer). Following piping placement, the trench willbe backfilled with imported road-base sand, compacted, and resurfaced to grade with asphalt. The proposed underground trenching location is depicted on Figure 3 ; a cross sectional view of the trench is depicted on Figure 4; a diagram depicting the proposed extraction manifold is illustrated in Figure 5 . 2.4 . PROPOSED INTERIM SOIL REMEDIATION SYSTEM The proposed SVE treatment unit will be a Mako Industries 250 TCAT (or similiar), which is comprised of a condensation separator, a vacuum blower, a thermal/catalytic oxidizer, and control components . The 2-inch diameter home-run piping installed from the well-heads at VW-1 through VW-4 will be connected to the inlet of the condensation separator, which leads into the vacuum blower;, the outlet fromthe vacuumblowerwillbe routedthrough a thermal heated catalytic oxidizer. The 250 TCAT would be modified for catalytic oxidation with the current concentrations below 3 ,500 parts per million volume (ppmv) . Induced vacuum will be measured utilizing a Magnehelic vacuum gauge attached to the inlet of the blower; SVE air flow will be monitored using a Dwyer DS-200 flow sensor. Sampling ports will be installed upstream of the vacuum blower inlet to recover SVE influent air flow vapor stream samples, and downstream of the oxidizer to recover effluent SVE air flow samples and to monitor the efficiency ofhydrocarbon destruction. A schematic diagram of the SVE treatment unit is depicted Advanced GeoEnvirontnental, Inc. „.